1. Field of the Invention
This invention relates to semiconductor device die packages, and more particularly to light emitting diode (LED) die packages.
2. Description of Related Art
It is known to provide semiconductor light emitting devices, such as a light emitting diode (LED), in a package that may provide protection, color selection, focusing and the like for light emitted by the light emitting device (LED package). An LED package generally includes a substrate member on which a light emitting device is mounted. The light emitting device may, for example, include an LED chip/submount assembly mounted to the substrate member with electrical connections being made to the LED for applying an electrical bias. It is understood in the art that LEDs generally comprise an active region of semiconductor material sandwiched between two oppositely doped layers. When a bias is applied across the doped layers, holes and electrons are injected into the active region where they recombine to generate light. Light is emitted omnidirectionally from the active layer and from all surfaces of the LED. The substrate member may also include traces or metal leads for connecting the package to external circuitry and the substrate may also act as a heat sink to conduct heat away from the LED during operation.
A reflector, such as the reflector cup, may be mounted on the substrate and surround the LED, with the reflector cup including an angled or sloped lower sidewall for reflecting light generated by the LED upwardly and away from the LED package. The reflector cup may also include upwardly-extending walls that may act as a cavity or opening surrounding the LED. After the LED and reflector cup are mounted on the substrate an encapsulating material, such as liquid silicone gel, can be dispensed into an interior cavity of the reflector cup. The reflective cup cavity has a bottom surface defined by the substrate to provide a closed cavity capable of retaining the liquid encapsulating material. A lens may then be placed over the reflector cup cavity in contact with the encapsulating material and the encapsulating material is typically cured to form the final die package.
The reflective cup can be silver plated in portions, such as on its angled or sloped lower sidewall, to further enhance its reflectivity. One conventional reflector cup comprises silver plated copper. A current LED die package manufacturing process includes a step of mounting the silver plated copper reflector to the substrate by an adhesive. It has been noted that the adhesive used to bond the reflector to the substrate may potentially cause the silver plated copper reflector to tarnish and its reflective properties to become degraded. The bonding step may also introduce variations in the relative height positioning between the reflector and other package components including the LED. This in turn may adversely affect the reflective capabilities of the reflector and the light output of the LED package.